Some theoretical considerations and experimental results concerning elastic-plastic stress-strain relations

1982 ◽  
Vol 52 (6) ◽  
pp. 391-403 ◽  
Author(s):  
Th. Lehmann
Keyword(s):  
Experimental Results ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Theoretical Considerations ◽  
Plastic Stress

Elastic-Plastic Stress Distribution in a Compressed Ring

1968 ◽  
Vol 90 (4) ◽  
pp. 435-440
Author(s):  
K. T. Chang ◽  
P. M. Leopold
Keyword(s):  
Stress Distribution ◽  
Strain Curve ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Strain Gages ◽  
Stress Strain ◽  
Theoretical Predictions ◽  
Strain Relationship ◽  
Plastic Stress

This investigation was conducted to define the plastic stress distribution at a section 90 degrees from the point of load application on a ring. The elastic and plastic stress distribution was determined experimentally by using postyield strain gages and the stress-strain relationship obtained from a uniaxial tensile test. The experimental results in the elastic range were found to agree with presently available theoretical predictions. A theoretical plasticity analysis of the ring was made by assuming that it deforms to the shape of an ellipse and that plane sections remain plane. The strains determined in this manner were used to calculate stresses off the tensile stress-strain curve. The experimental results indicated that this initial analysis gave a good approximation of the stress distribution for large deflections of the ring.

Versatile Elastic-Plastic Stress-Strain Formula

1975 ◽  
Vol 101 (4) ◽  
pp. 511-515 ◽  
Author(s):  
Ralph M. Richard ◽  
Barry J. Abbott
Keyword(s):  
Stress Strain ◽  
Elastic Plastic ◽  
Plastic Stress

Multiaxial Stress Concentration in an Externally Pressurized Cylinder With an External Circumferential Groove

1995 ◽  
Vol 117 (4) ◽  
pp. 404-409
Author(s):  
S. M. Tipton ◽  
K. A. Hickey ◽  
M. S. Rawson ◽  
J. R. Sorem
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Axial Strain ◽  
Radial Strain ◽  
Strain Ratio ◽  
Experimental Results ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Circumferential Groove ◽  
Neuber's Rule

A thick-walled cylindrical specimen containing an external circumferential groove was subjected to external pressure. To investigate the maximum pressure sustainable by the reduced wall thickness, strain gage measurements were taken during external pressurization tests. For comparison to experimental results, an elastic-plastic notch stress-strain analysis was conducted based on Neuber’s rule. The analysis utilized multiaxial elastic finite element results along with elastic-plastic tensile test data for the cylinder material. Based on experimental observations, it was necessary to supplement the approach with an additional relation between elastic and elastic-plastic multiaxial strains for the axisymmetric geometry under investigation. Assuming an invariant hoop to radial strain ratio rather than an invariant hoop to axial strain ratio provided better agreement with experimental results. It is demonstrated that the boundary conditions used to model the specimen had a substantial effect on the finite element results, even though the boundary was somewhat removed from the region of concentrated stress. Biaxial strain measurements are presented versus pressure over the elastic and into the plastic regime, and deformation plasticity theory was used to compute stress and radial strain components corresponding to measured strains. It is demonstrated that in order to apply a multiaxial Neuber’s rule to accurately estimate the elastic-plastic stress-strain response (using elastic stress concentration information and elastic-plastic material data), it is necessary to utilize an experimental observation that the ratio of the hoop to radial strain remains invariant from the elastic to the elastic-plastic regime. This differs from published assumptions about invariant hoop-to-axial strain ratios based on analysis of circumferentially grooved solid shafts. The predictions are accurate for moderate plastic strains, but correlation breaks down for bulk plastic deformation.

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